Field of the Invention
The present invention relates to a variable valve lift apparatus. More particularly, the present invention relates to a three-point supported variable valve lift apparatus that is supported on two valves and one hydraulic lash adjuster.
Description of Related Art
In general, internal combustion engines generate power by receiving and burning air and fuel in a combustion chamber. When an intake valve is operated by a camshaft, air is drawn into the combustion chamber with the intake valve open. Further, when an exhaust valve is operated by the camshaft, air is discharged from the combustion chamber with the exhaust valve open.
The optimum operation of the intake valve or the exhaust valve depends on the RPM of the engine. That is, appropriate timing for lifting or opening/closing the valves is controlled on the basis of the RPM of the engine. In order to appropriately operate valves in accordance with the RPM of an engine, as described above, a VVL (Variable Valve Lift) apparatus that operates valves at different lifts in accordance with the RPM of an engine has been studied. As an example of the variable valve lift apparatus, there is an apparatus that includes a plurality of cams on a camshaft for operating valves at different lifts, and is operated such that the cams for operating the valves are selected in accordance with circumstances.
However, when a plurality of cams is provided on a camshaft, a configuration for switching the cams to operate an intake valve or an exhaust valve is complicated and there may be interference between components. On the other hand, when a plurality of cams is independently operated to prevent interference between components, components for operating the cams are additionally required, so the manufacturing cost may be increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.